What is a Sty (Stye)?

A sty is a bump that forms on or in the eyelid as the result of a blocked gland. The word "sty" can also be spelled "stye." There are two distinct types of stys: hordeolum and chalazion. Each has different causes and treatments.

A hordeolum is a blockage of one of the sweat glands found in the skin of the lid and base of the eyelashes, or one of the small sebaceous glands found at the base of the eyelashes. Sebaceous glands secrete sebum, a waxy, oily material.

A chalazion is a blockage of a meibomian gland, which is a special sebaceous gland unique to the eyelids. These glands form a single row in each lid, with the body of the gland located inside the eyelid, and the opening located at the rim of the lid, posterior to the lashes. They secrete an oily material onto the surface of the eye, preventing the water layer of tears from evaporating too rapidly from the eye's surface between blinks. Therefore, poorly functioning meibomian glands can lead to dry eye symptoms.

What causes a Sty (Stye)?

Styes occur when a gland in or on the eyelid becomes plugged or blocked. This can occur if the gland's opening is obstructed by scar tissue or a foreign substance (makeup, dust), or if there is thickening of the substance produced by the gland, causing the material to flow sluggishly or not at all.

Patricia S. Bainter, MD

Dr. Bainter is a board-certified ophthalmologist. She received her BA from Pomona College in Claremont, CA, and her MD from the University of Colorado in Denver, CO. She completed an internal medicine internship at St. Joseph Hospital in Denver, CO, followed by an ophthalmology residency and a cornea and external disease fellowship, both at the University of Colorado. She became board certified by the American Board of Ophthalmology in 1998 and recertified in 2008. She is a fellow of the American Academy of Ophthalmology. Dr. Bainter practices general ophthalmology including cataract surgery and management of corneal and anterior segment diseases. She has volunteered in eye clinics in the Dominican Republic and Bosnia. She currently practices at One to One Eye Care in San Diego, CA.

William C. Shiel Jr., MD, FACP, FACR

Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.